1. Technical Field
Embodiments of the present disclosure are generally directed to a stereoscopic image display device, and more particularly, to a stereoscopic image display device capable of performing a mutual conversion between a 2 dimension (2D) image and a 3D image.
2. Discussion of the Related Art
Among various technology developments, a demand for and development of a stereoscopic image display which does not use glasses has continuously progressed.
To display a 3D image without using glasses in an existing flat display device, binocular disparity is used, in which the left and right eyes of an observer view different images. The method is traditionally implemented using a lenticular lens or a parallax barrier. A method using only a lenticular lens or a parallax barrier may implement a 3D image, but is affected by issues such as resolution deterioration, moiré patterns, etc. Therefore, methods such as simultaneously using a barrier and a lens, have been studied.
One issue in existing display devices having a 2D image/3D image conversion structure is that the resolution of 3D image deteriorates more than that of the 2D image. To improve the resolution, a direction controllable backlight unit (BLU) method has been adopted, which controls light emitted from a backlight unit (BLU).
In a general LCD structure, a direction controllable BLU method can temporally separate and control directions of light emitted from a backlight unit (BLU) by combining a parallax barrier and a lenticular lens between a display panel and the backlight unit that can effectively switch between a 2D image and a 3D image without changing resolution.
However, most autostereoscopic 3D structures are characterized in that a 3D image may only be perceived at a specific distance from the display device, and it can be challenging for a user to find that specific distance.
A lenticular lens and a parallax barrier are typical devices for controlling light distribution for displaying a 3D image in an conventional direction BLU structure. Basically, a parallax barrier is an active device such as a liquid crystal (LC) that can transmit/block an optical path, and a lenticular lens is a passive device in a film form.
A lenticular lens film can separate the optical path of the left and right eyes to display a 3D image, however, only users who are at a specific distance may perceive the 3D image due to a fixed curvature radius. A viewing distance may be partially controlled based on positions before and after a user has moved by controlling a width of a barrier but issues of luminance deterioration, the occurrence of dark portions, etc., remain.